The use of polymers with optical brightener agents copolymerized within the polymer are known in the art. These polymers have been used to prepare articles that contain products that are sensitive to UV light.
U.S. Pat. No. 4,882,412 to Weaver et al. discloses a polyester composition useful for molding into articles. The polyester composition was copolymerized with a residue of a 7-oxy-2H-1-benzopyran-2-one compound or a 7-oxy-2H-1-benzopyran-2-imine compound, which are ultraviolet compounds. U.S. Pat. No. 4,803,241 to Weaver et al. discloses a polymer composition composed of a polyester or polycarbonate copolymerized with a styrylbenzyoxazole compound.
U.S. Pat. No. 4,095,939 to Pacific et al.; U.S. Pat. No. 2,657,194 to Butler et al.; U.S. Pat. No. 3,709,896 to Frischkom et al.; and U.S. Pat. No. 2,657,195 to Toland et al. also disclose the copolymerization of ultraviolet absorbing compounds with polyesters. None of the references described above disclose the copolymerization of a sulfonate-containing monomer with the polyester and the ultraviolet absorbing compound. Thus, these polymers are not water dispersible polymers of the present invention.
U.S. Pat. No. 4,177,347 to Meyer discloses a process for the preparation of distilbenzyl-oxadiazoles and their use for optically brightening organic materials. The distilbenzyl-oxadiazoles possess a carboxyl group and sulfonate group. Meyer, however, does not disclose the copolymerization of a polyester with an ultraviolet fluorescent agent and a sulfonate-containing monomer.
U.S. Pat. Nos. 5,082,578 and 5,039,782 to Langer et al disclose the preparation of polymeric whitening agents. The copolymers contain both a fluorescent portion and a hydrophilic portion. Hydrophilic monomers that are useful include alkylene glycols such as ethylene glycol, propylene glycol, and butylene glycol. Other hydrophilic monomers include sugars such as glucose, sucrose, sorbitol, or glycerol. Surface active agents can also be added. Langer et al does not disclose the use of a sulfonate-containing monomer for the preparation of the copolymer. In addition, the surface active agents disclosed in Langer et al. are not sulfonate-containing monomers of the present invention.
The incorporation of near-infrared fluorescent agents into polymers has also been disclosed in the art. U.S. Pat. Nos. 5,292,855; 5,336,714; and 5,423,432 to Krutak et al. disclose the preparation of water-dissipatible, sulfo-containing polyesters and polyamides with near-infrared fluorescent compounds copolymerized within the polymer. There is no disclosure or motivation in these references to use an optical brightener compound in place of or in addition to the near-infrared compound to produce the present invention.
In light of the above it would be very desirable to produce water-dispersible polymers with optical brightener compounds copolymerized within the polymer. The present invention, as described below, relates to water-dispersible polymeric compositions that are useful in the formulation of optical brightener inks, paints and film forming compositions. The water-dispersible polymeric compositions are unique in that the optical brightener compounds are not extractable, exudable, sublimable or leachable from the polymeric composition. Also, since the optical brightener compounds are bound to polymer chain by covalent bonds or incorporated into the backbone of the polymer by covalent bonds, toxicological concerns are minimized because of low potential for exposure to humans.
Another object of the present invention is to enhance the optical brightness of an article or composition. Articles or compositions contacted with a polymer containing an optical brightener compound of the present invention can offset any discoloration in the article or composition.
Another object of the present invention is to prepare articles or compositions from the polymeric compositions. In one embodiment, the inks, paints and film forming compositions prepared from the polymeric compositions of this invention are especially useful in "marking" or "tagging" various items such as security documents, bank checks and other printed or coated materials where subsequent detection or identification is desired.
In another embodiment of the present invention, the polymeric compositions possess optical brightener and near-infrared fluorescent agents either as separate polymers or copolymerized together. Therefore, articles or compositions prepared from the polymeric compositions of the present invention have an additional advantage over prior art articles or compositions in that they can be detected by exposing these articles or compositions either or both to near-infrared and ultraviolet light.